Sphingosine 1-phosphate receptor type 1 as a novel target for the therapy of autoimmune diseases

Sphingosine 1-Phosphate Receptor Subtype 1 as a Therapeutic Target for Brain Trauma

Traumatic brain injury (TBI) provokes secondary pathological mechanisms, including ischemic and inflammatory processes. The new research in sphingosine 1-phosphate (S1P) receptor modulators has opened the door for an effective mechanism of reducing central nervous system (CNS) inflammatory lesion activity. Thus, the aim of this study was to characterize the immunomodulatory effect of the functional S1PR1 antagonist, siponimod, in phase III clinical trials for autoimmune disorders and of the competitive sphingosine 1-phosphate receptor subtype 1 (S1PR1) antagonist, TASP0277308, in pre-clinical development in an in vivo model of TBI in mice. We used the well-characterized model of TBI caused by controlled cortical impact. Mice were injected intraperitoneally with siponimod or TASP0277308 (1 mg/kg) at 1 and 4 h post-trauma. Our results demonstrated that these agents exerted significant beneficial effects on TBI pre-clinical scores in term of anti-inflammatory and immunomodulatory effects, in particular, attenuation of astrocytes and microglia activation, cytokines release, and rescue of the reduction of adhesion molecules (i.e., occludin and zonula occludens-1). Moreover, these compounds were able to decrease T-cell activation visible by reduction of CD4⁺ and CD8⁺, reduce the lesioned area (measured by 2,3,5-triphenyltetrazolium chloride staining), and to preserve tissue architecture, microtubule stability, and neural plasticity. Moreover, our findings provide pre-clinical evidence for the use of low-dose oral S1PR1 antagonists as neuroprotective strategies for TBI and broaden our understanding of the underlying S1PR1-driven neuroinflammatory processes in the pathophysiology of TBI. Altogether, our results showed that blocking the S1PR1 axis is an effective therapeutic strategy to mitigate neuropathological effects engaged in the CNS by TBI.

An oral sphingosine 1-phosphate receptor 1 (S1P(1)) antagonist prodrug with efficacy in vivo: discovery, synthesis, and evaluation

A prodrug approach to optimize the oral exposure of a series of sphingosine 1-phosphate receptor 1 (S1P(1)) antagonists for chronic efficacy studies led to the discovery of (S)-2-{[3'-(4-chloro-2,5-dimethylphenylsulfonylamino)-3,5-dimethylbiphenyl-4-carbonyl]methylamino}-4-dimethylaminobutyric acid methyl ester 14. Methyl ester prodrug 14 is hydrolyzed in vivo to the corresponding carboxylic acid 15, a potent and selective S1P(1) antagonist. Oral administration of the prodrug 14 induces sustained peripheral blood lymphocyte reduction in rats. In a rat cardiac transplantation model coadministration of a nonefficacious dose of prodrug 14 with a nonefficacious dose of sotrastaurin (19), a protein kinase C inhibitor, or everolimus (20), an mTOR inhibitor, effectively prolonged the survival time of rat cardiac allografts. This demonstrates that clinically useful immunomodulation mediated by the S1P(1) receptor can be achieved with an S1P(1) antagonist generated in vivo after oral administration of its prodrug.

Fingolimod (FTY720), sphingosine 1-phosphate receptor modulator, shows superior efficacy as compared with interferon-β in mouse experimental autoimmune encephalomyelitis

Fingolimod (FTY720), a sphingosine 1-phosphate (S1P) receptor modulator, inhibits S1P-dependent lymphocyte egress from secondary lymphoid organs and is highly effective in experimental autoimmune encephalomyelitis (EAE) in mice. In this study, we directly compared the therapeutic effects of FTY720 and recombinant mouse interferon (rm-IFN)-β on relapse and progression of EAE in mice. When FTY720 at oral dose of 0.03 to 1 mg/kg was administered daily after establishment of EAE induced by myelin proteolipid protein (PLP) in SJL/J mice, relapse of EAE was significantly inhibited during administration period. Subcutaneous injection of rm-IFN-β (10,000 IU/mouse) also inhibited the relapse of EAE at early period; however EAE was relapsed in all the mice within administration period. Therapeutic administration of FTY720 (0.03 to 1 mg/kg) significantly improved the symptoms of chronic EAE induced by myelin oligodendrocyte glycoprotein in C57BL/6 mice whereas rm-IFN-β (10,000 IU/mouse) showed no clear effect. These results indicate that FTY720 is more efficacious in mouse EAE as compared with rm-IFN-β. FTY720 markedly reduced the frequency of PLP-specific Th17 and Th1 cells in the spinal cord of EAE mice. On the contrary, FTY720 increased the frequency of PLP-specific Th17 and Th1 cells in the inguinal lymph nodes, suggesting inhibition of egress of myelin antigen-specific Th cells from draining lymph nodes. From these results, the ameliorating effects of FTY720 on EAE are likely due to reduction of infiltration of myelin antigen-specific Th17 and Th1 cells into the central nervous system.